Bone Plate Tensioning System for Osteopenic Fracture Fixation

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional bone fracture fixation methods, such as screw fasteners, fail to provide stable fixation in osteopenic bone and require a large inventory of different sizes, are prone to breakage, and can be invasive, while cerclage systems may injure the bone and inhibit healing.

Innovation Solution

A fracture fixation system using a bone plate with elongated tension elements, such as braided metal cables, that pass through the bone and are anchored with proximal and distal anchors, allowing for adjustable tension and minimally invasive procedures, reducing the need for multiple screw sizes and minimizing tissue disruption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If screw fasteners are used to fix the bone plate to the bone, then the bone plate can be held tightly against healthy bone, but the screw threads fail to find adequate purchase in osteopenic bone to maintain proper alignment

Engineering Contradiction:

Improvefixation stabilityVSAvoidapplicability to osteopenic bone

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The invention changes the fixation mechanism from thread-based engagement to friction-based engagement. The bone anchors have a friction fit within bone tunnels, and the tensioning mechanism applies compressive force across the fracture site. This parameter change allows the system to work in osteopenic bone where threads cannot gain adequate purchase, while still providing stable fixation.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention replaces the mechanical screw thread engagement system with a tensioning system using bone anchors and tensioning members. Instead of relying on threaded fasteners to create clamping force, the system uses independently anchored tension members that are tensioned to apply compression across the fracture, substituting a different mechanical principle that is effective in osteopenic bone.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Adaptability or versatility

If a large variety of screw sizes are made available to accommodate variations in patient anatomy and fracture type, then appropriate fixation can be achieved, but the inventory cost and complexity increase significantly

Engineering Contradiction:

Improveaccommodation of anatomical variationsVSAvoidinventory of screw sizes and associated instrumentation

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The invention creates a universal fixation system where a single bone anchor design and tensioning mechanism can be used across different bone sizes and fracture types. The system adapts to anatomical variations through the length and tensioning of the members rather than requiring different sized fasteners, eliminating the need for large inventories of specialized screws and associated drilling equipment.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Reliability

If cerclage cables are used to hold fracture fragments together, then fixation can be achieved, but the cable exerts significant line pressure against the periosteum that may injure the bone and inhibit healing

Engineering Contradiction:

Improvefracture fragment stabilizationVSAvoidline pressure on periosteum

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The invention uses a tensioning member that distributes force more evenly across the bone surface rather than concentrating line pressure at a single point. The flexible nature of the tensioning system allows it to conform to the bone geometry while maintaining stabilization, reducing the harmful concentrated pressure that cerclage cables exert on the periosteum.

Inventive Principle:

Principle #30Flexible shells and thin films

4Reliability

If screw fasteners are used for internal fixation, then the bone plate can be secured to the bone, but the screws are prone to breakage due to stress concentrations from poor load sharing and high cyclic loading

Engineering Contradiction:

Improvebone plate attachmentVSAvoidresistance to screw breakage

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The invention segments the load-bearing function across multiple independent bone anchors and tensioning members rather than concentrating stress in screw threads. Each bone anchor independently engages the bone, and the tensioning members distribute cyclic loads more evenly, preventing the stress concentrations that lead to screw breakage while maintaining secure bone plate attachment.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS7837717B2Fastening system for internal fixation

Publication Date: 2010.11.23 ZIMMER GMBH

AI summary

A bone fracture fixation system comprises a bone plate configured to bear against a proximal surface of the bone and a plurality of elongated tension elements, each sized to pass through an opening in the bone plate and through the bone from the proximal surface to a distal surface thereof. Each tension element is anchored to the bone and maintained in tension by a distal anchor attached to said tension element and configured to engage the distal surface of the bone and a proximal anchor engageable between the bone plate and the tension element. In one method for fixation of a bone fracture, the bone plate is positioned on a proximal surface of the bone while the tension element is introduced into the bone and through an opening in the bone plate from an opposite distal surface of the bone.